1. The Field of the Invention
The present invention relates to a method for preparing a cyclohexyl phenyl ketone from a 1,3 butadiene and acrylic acid without a purification or separation step and, more particularly, to a synthesis method of cyclohexyl phenyl ketone that includes carrying out a [2+4] Diels-Alder reaction of 1,3-butadiene and acrylic acid in the presence or absence of benzene or a non-aromatic organic solvent to yield 3-cyclohexene-1-carboxylic acid, a hydrogenation reaction to yield cyclohexanecarboxylic acid, a chlorination reaction to prepare a cyclohexanecarbonyl chloride; and a Friedel-Crafts reaction in the same reactor without purifying or separating the cyclohexanecarboxylic acid to prepare a cyclohexyl phenyl ketone with a high yield.
2. Related Prior Art
In general, cyclohexyl phenyl ketones are used as an intermediate of 1-hydroxy cyclohexyl phenyl ketone that is used as a photoinitiator in a photopolymerization reaction of unsaturated compounds and a photochemical cross linking reaction of polyolefins.
The potoinitiator is a curing agent that temporarily converts a liquid material to a solid resin using an ultraviolet radiation, and widely applied for a UV coating material, a UV ink, etc., in the manufacture of special high gloss furniture, wrapping paper printing, or high gloss plastic floor material.
The most generally used method for preparing a cyclohexyl phenyl ketone involves hydrogenation of benzoic acid under the condition of high temperature and high pressure, purification for removal of by-products to yield a cyclohexanecarboxylic acid, conversion of the purified cyclohexanecarboxylic acid to a cyclohexanecarbonyl chloride (Ref. Organic Synthesis, col. Vol. IV, 339-342), and Friedel-Crafts reaction with benzene in the presence of anhydrous aluminum trichloride.
This method, which produces a cyclohexyl phenyl ketone with a high yield, requires a condition of high temperature and high pressure for the hydrogenation reaction of benzoic acid, with the difficulty in regard to production facilities, and the purification step for removing by-products of the hydrogenation reaction.
Another known synthesis method of cyclohexyl phenyl ketones involves reacting cyclohexanecarboxylic acid with benzoic acid in the presence of a manganate catalyst such as manganese carbonate (MnCO3), as disclosed in UK Patent Nos. 1,030,003 and 1,063,268. This method has the difficulty in regard to production facilities due to high reaction temperature(280˜450° C.).
U.S. Pat. No. 4,950,763 discloses a method of preparing a cyclohexyl phenyl ketone from cyclohexanecarboxylic acid and benzoic acid in the presence of a titanium oxide catalyst including alkali oxides by a gas phase reaction, which method is inferior in selectivity. U.S. Pat. No. 3,660,491 also discloses a method of preparing a cyclohexyl phenyl ketone from cyclohexanecarboxylic acid and benzoic acid. This method is carried out in the presence of a cobalt catalyst at a low temperature of below 200° C. but with a low conversion rate.
In addition, UK Patent No. 1,066,542 discloses a synthesis method of a cyclohexyl phenyl ketone from cyclohexanecarboxylic acid and benzene in the presence of polyphosphate, which method has a very low product yield.